Hydraulic operator



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W. J. WOODS HYDRAULIC OPERATOR Filed Sept. 30,

March 14, 1933.

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Patented Mar. 14, 1933 UNITED STATES PATENT OFFICE WILLIAM J'. WOODS, OF SGHENEUIVADY, NEW YORK, ASSIGNOR TO GENERAL ELECTRIC COMPANY, A. CORPORATION OF NEW YORK HYDRAULIC OPERATOR Application led SeptemberO, 1930. Serial No. 485,474.

My invention relates to electro-hydraulic operating means of the general character described and claimed in a copending application of Walter 0. Lum, Serial No. 415,341,

filed December 19, 1929 and assigned to the assignee of the present invention.

ln the device of the Lum application referred to above to obtain compactness the movable piston carries and houses the pressure generating im eller concentrically therein, a splined sha t permitting relative movement between the impeller and the stationary driving motor therefor as the piston is moved. With this construction all of the fluid must pass through the impeller both upon operation of the impeller to raise the piston as well as when the driving motor -is deenergized to permit the piston to return toits initial position. This results in a piston construction of rather complicated design which restricts the passage of oil. Furthermore, in order to create the pressure necessary for quick operation of the piston,

impellers of large diameter relative to the piston and of correspondingly large moments of inertia have been used. The large moment of inertia of the impeller as well as the materially restricted oil passages through the piston hinder a quick return of the piston which in certain service is one of the requirements for a device of this character.

Hence it is the principal object et my invention to provide an improved concentric type of electro-hydraulic operating device which is compact but in which complicated piston structures are eliminated and quicker reset of the piston upon deenergization ofV the device is obtained.

ln the preferred embodiment of my invention l provide the fluid casing for the concentric piston and impeller with a cylinder or sleeve formed with passageways for the passage of oil around the piston which slides in the sleeve. ln addition aconcentric oil tube extends from the top of the casing through the piston and cooperates with the cylinder to form a stationary housing for the impeller which is driven by an electric motor mounted on the top of the casing,`

the` driving shaft extending downwardly through the oil tube.

comparison to the diameter of the impeller in order to deliver a large volume of oil to the under side of the piston. The wide blades of small diameter permit theuse of the same size motor as previously used without overload to deliver a volume of oil necessary for fast operation. With this construction a very compact` unit is obtained by arranging the impeller and piston in concentric cooperating relationship with the minimum amount of space necessary to house both elements. Also since the impeller does not move with the piston the splined shaft The impeller is spe-- .cially designed with relatively wide blades in is eliminated and thev piston structure is greatly simplified having simply ain opening therein to permit the extension of the'oil tube therethrough. Moreover with the specia-ll designeddmpeller and the large and gra ually curving passageways in thehousing the piston will reset rapidly, upon deenergization of the driving motor, the oil owing 'freely through the orifices and through and around the piston, making it necessary for only part of the oil to pass through the piston, thus increasing the rate of flow of oil to the upper side of the piston which increases the speed with which the piston will return to initial position.

In the drawing Fig. 1 shows a cross section of my invention and Fig. 2 shows a detailed construction of the cylinder used in the hydraulic operator shown in Fig. 1. Fig. 3 is a graph showing time load relationshi for the hydraulic operator.

n Fig. 1 the casing 10 is provided with the cover 11 which supports the electric motor l2 which drives the impeller 19 by means of the shaft 20. Within the casing 10 is the sleeve or cylinder 13 having a head 13 with an opening therethrough and supported by the abutment 10 of the casing 10 and secured thereto by means of the pin 15. The oil tube 17 is fastened to the cover 11 by suitable screws and extends toward the `cylinder head 13 by means of its iared end 171 and forms therewith a housing for the impeller 19. This housing provides passagespacing elements 14 `as shown in Fig. 2.-

Thus passageways such as 16 are provided between the casing 10 and the cylinder which permit the oil to reach the underside of the impeller 19 around the piston 21. Oil is also ledv to the top of the impeller 19 through the oil tube 17 provided with the openings '18 therein, it being noted that the oil level The piston 21 is above these openings. slides within the sleeve 13 and has an opening therein through which the oil tube 17 extends. Supported by the piston 21 are the push rods 22 and 23 having a bridging member 24 supporting the work engaging eye 25. The casing 10 is provided with the eye 26 permitting pivotal support of the entire unit.

One of the most desirable characteristics in certain service of fluid pressure operated devices such as my hydraulic operator is to have a quick operation and quick reset of the piston. I have found that by increasing the relative width of the blades of the impeller with respect to the diameter a greater volume of oil can be delivered without over' loading the motor. This is due to the fact that although the blades are made wider the load on the motor increases more rapidly with an increase in the diameter of the impeller blades than with an increase in the width of the blades. The resulting low moment of inertia of the impeller and oil entrapped therein causes it to quickly come to rest when the motor is deenergized, thus minimizin the delay in the starting of the reset of t e piston to its initial position. This calls for larger orices in the impeller housing which decreases the turbulence of the flow of oil through the housing. Making the impeller stationary and extending the drive shaft through the piston proper makes it possible to greatly simplify the passageways of the impeller housing as 'can clearly be seen from Fig. 1. The simplified passageways in the housing proper, and the passageways provided for by-passing the oil around the piston instead of passing the entire volume of oil through the piston proper permits a very rapid return of the piston upon deenergizationof the impeller since unrestricted passageways are thereby provided for the return flow of the oil.

The time load relationship for' normal working loads of my new design operator are shown in Fig. 3, the time being marked in tenths of a second along the X axis and the load in pounds along the Y axis. Of course these relationships `will not hold when absolute maximum loads other than those for which the operator is designed are applied to the operator. Curve 1 represents the time required for thelvarious loads be fore the piston starts to settle; curve 2 the time required after starting for the travel of the piston from its upper position to its lower position. Curve 3 shows the total time required for the various loads; curve 4 the time required before the piston starts in its upward movement; curve 5 thetime required for the piston to move from its lower position to its upper position and curve 6 the total time required for movement of the piston from its lower position to its upper position. Curve 7 is an approximate represent-ation of the time required for resetting of the prior type of hydraulic operator referred to above in the Lum ap lication.

It will be seen that curves 2and 3 s ow that the time-required.for'resetting, that is for the piston` to move from its upperto its lower position upon deenergization of the operatoris substantially independent of the load operated upon between limits -for which the operator is designed which was not true of` the old type of operator as can be seen from the approximate curve 7. It will be noted further that for a given operator there is one load where the total time required for resetting and the total time required for movement to the upper position are the same. This load, therefore, when applied to the operator will cause the operator to` move to either position in the same length of time. Practically the entire operation of the device is completed within a few tenths of a second, the curves being taken from .an -actual test run upon the new type of operator. The ideal condition, of course, would be to have the operator reset within 4the same length of time independently ofall loads which condition is substantially provided by my new type of operator. It will be also observed that the time for resetting with ,a minimum load is not greater than the time for operation of the operator to its upper position with a maximum load as can be det-Tlimined from a study of the curves #3 and to the under side of the impeller. It will thus be observed that only part of the oil must pass through the piston. The impel- 1er forces the oilv in a radial direction through the passageway 17 thus creating a pressure differential between opposite rllhe operation ofl the device is as follows:

sides of the piston 21 to move it upwardly in a vertical direction. reaches its upper limit the im eller continues to'provide a pressure di erential to support the piston without delivering more oil to the underside of the piston proper. In this upper position of the piston the impeller will spin in the oil to maintain the pressure differential. Upon deenergization of the driving motor 12 the impeller quickly comes to a standstill as the energy of the rotor of the motor is expended and the pressure soon drops, permitting the piston to return to its initial position. This return or reset of the piston is rapid because the passageways provided in the housing as explained above are devoid of complicated turns and are large and because only part of the oil needs to pass through the piston proper, substantially half of the oil being by-passed around the piston by means of the cylinder and casing combination.

It will thus be seen that I have provided a fluid pressure operated device or hydraulic operator in which Ihave greatly simplified the construction and in which I provide quick reset of the piston which heretofore has been impossible with hydraulic operated piston designs of more or less complicated structure.

The embodiment of the invention illustrated and described herein has been selected for the purpose of clearly setting forth` the priciples involved. It will be apparent, however, that the inventionv is susceptible of being modified to meet the different conditions encountered in its use, and I, therefore, aim to cover by the appended claims all of the modifications within the true spirit and scope of my invention. l

What I claim as new and desire to /secure by Letters Patent of the United States, i

casing, a piston operable in the casing, and a pump immersed in the fluid and having its inlet and outlet passages connected to create a differential in the fluid pressure on the opposite sides of the piston to move said piston, a housing for said pump, and a fiuid guide tube extending through the piston, said tube providing a fluid inlet to said pump housing. 0

2. A hydraulic operator including a fluid container, a, cylinder immersed in the Huid in said container, a piston movable in the cylinder, and a double inlet impeller pump mounted at the head end of the cylinder and discharging therein for creating a differential in the fluid pressure on the opposite sides of the piston, and having one inlet extending throughA the headof the cylinder and the other 'inlet extending through the piston.

When the piston 1. A hydraulic operator including a fiuid 3. A hydraulic operator including an im pell'er pump immersed in a fluid, a pair of separable concentrically disposed tubes having means at the adjacent ends thereof forming a housing for said impeller with the discharge directed between the tubes,

said tubes providing inlet passages to said impeller pump and an annular piston disposed between the tubes to be operated. by

the fluid pressure created uponl rotation of the impeller.

4. A hydraulic operator includin ble inlet impeller immersed in a uid, an inlet tube for one side of the impeller having means at the end thereof forming one side of a separable housing for the impeller, a cylinder concentrically surrounding the tube and the impeller and having a head forming the other side of said separable housing `provided with an inlet for the other side of the impeller, the discharge of said housing being directed into thespace betwen the tube and the cylinder, and a piston having a sliding engagement with the outside of the tube and the inside of the cylinder to be operated by the fluid pressure created upon rotation of the impeller in said housing.

a ydou- 5. A quick reset hydraulic operator including a fluid casing, a piston movable in the casing between two positions, a work' engaging member connected thereto, an inipellei` pump mounted at one end of the casing for creating a pressure differential in the fiuid on opposite sides of the piston to move said piston to one of said positions, a housing for said pump', a fluid guide tube extending through said piston and providing an inlet to said housing, said piston sliding on said tube, said impeller pump being designed for a given loady to permit a return movement of said piston to its other position in the substantially same length of time required for movement to said one position.

6. A. quick reset hydraulic operator provided with afluid casing, a piston immersed in a fluid therein and movable between two piston to its other position, the time for l said movement being substantially independent of the load engaged by said work engaging member between wide limits.

7 A quick reset hydraulic operator provided with a fluid casing, a piston immersed in a fluid therein and movable between two positions, a load engaging member connected thereto for engaging loads of various' degrees, an impeller pump therein for creating a pressure differential to move said piston to one position, a housing for said pump having a fluid guide tube for conducting fluid to said pump housing through said piston, said piston sliding on said tube, said pump and tube being designed so that the time required for the piston to move to its other position with minimum load is not greater than the time for movement to said one position with maximum load.

8. A quick reset operator including a piston immersed in a liquid and movable between two positions, a double inlet impeller for creating a pressure diferential to o erate said piston, means for conducting uid through said piston and around said iston to both sides of said impeller, said 1mpeller being designed with relatively wide blades in comparison with its diameter whereby a large volume of fluid is quickly delivered to the face of the piston to obtain rapid movement thereof to one position, said conducting means forming a housing having gradual curved passageways permitting a free return flow of fluid through said housing without turbulence to permit a rapid rmovement of said piston to its other position, the time for movement of said piston to said one position being for a given load substantially equivalent to ythe time fo movement toits other position.

9. A quick reset hydraulic operator including a piston immersed in a liquid and movable between two positions, a pressure creating impeller for moving said piston to one of said positions, said impeller being of such proportions as to dellver a relatively large volume of liquid in operation, a means for conductin liquid through said piston to one side o sald impeller, other means for conducting fluid around said piston to the other side of said impeller, said conducting means providing a housing for said impeller and having relatively radual curved passageways permitting a ree return flow of fluid through said housing to permit a rapid movement of said piston to its other position.

10. A hydraulic operator includin a Huid casing, a iston immersed in a lui therein and Inova le between two positions, an impeller for creating a pressure differential for moving said plston to one of said positions, means for conducting iuid through said piston to one side of said impeller, a cylinder in said casing in which said piston moves and passageways formed by said cylinder and casing for directing fluid to the other side of said impeller, sald conducting means and passageways providing return means for the fluid when said piston moves to the other position.

11. A hydraulic yoperator includn a fluid casing, a piston, an impeller pum aving a drive shaft extending throng said piston, said piston having relative movement with respect to said impeller, a cylinder provided with a head integral therewith within said casing in which said piston moves, a fluid tube having a flared end extending through said piston and concentric of said drive shaft, the flared end of said tube and the head en d of said cylinder forming a housing for said impeller pump.

12. A hydraulic operatorincluding a fluld casing, a fluid therein, an impeller pump having a drive shaft centrally disposed in said casing, a tube-concentric of said im'- peller shaft and provided with a flared end, a cylinder provided with a head integral therewith mounted in saidl casing, the head end of said cylinder and the ared end of said tube forming a housing for said impeller pump, and a piston immersed in said fluid within said cylinder, said tube extending through said piston, said piston being movable with respect to. said tube in response to operation of said impeller pum 13. A hydraulic operator including a iiuld casing, a fluid therein an electric driving means mounted at one end of said casing, an impeller rotatably mounted and centrally disposed in said casing and connected to be driven by said driving means, a fluid guide tube extending within said casing, a cylinder in said casing, a piston immersed in said luid within said cylinder and movable therein, said tube extending through said piston, said cylinder and tube forming a housing for said impeller, said piston having a movement parallel to said tube in response to o ration of said impeller.

14. A hyaulic operator includin a fluid casing, a cylinder mounted in sai casing and providing passageways between the cylinder and said casing, a iuid tube disposed centrally of said casing and extendin toward and adjacent said cylinder, a piston movable in said cylinder, said tube extending through said piston, said piston being slidable thereon, a double inlet impeller having a shaft extending through said tube, said tube and cylinder forming a housing for said impeller on one side of said piston, said impeller receiving fluid through said tube and said passageways formed by saidcylinder and casing and expelling the same through the housing formed by said tube and cylinder in a radial direction to create a pressure differential on one side of said piston whereby said piston will move in response thereto.

15, A quick reset hydraulic operator including a fluid casin an electric motor mounted at one end o said casing, an impeller rotatably mounted and centrally dis- I posed in said casing and connected to be driven by said motor, said impeller being designed to deliver a relatively lar e volume of fluid during operation, a flui guide tube extending within said casing, a cylinder in said casing, a piston within said cylinder movable between two positions, said tube extending through said piston, said piston having a movement parallel to said tube to one position in response to operation of said impeller upon energization of said motor, said cylinder and tube forming a housing having relatively gradual curved passageways for said impeller permitting a free return low of fluid through said housing to permit a rapid movement of said piston to its other position upon deenergization of said driving means.

16. A hydraulic operator including a Huid container, a piston movable therein, a double inlet impeller for discharging iuid under pressure against one side of said piston, and a tube extending through said piston for conducting Huid from the other side of said piston to one inlet of said pump, and other means for conducting fluid from said container to the other inlet of said pump.

17. A hydraulic operator including a Huid container,`a piston movable therein, a load engaging member connected thereto, an impeller pump mounted in the bottom of said container for discharging iuid against one side of said piston to move the same, a housing for said pump and a fluid inlet tube extending through said piston to an intake of the pump housing for conducting fluid from the other side of the piston to said pump housing, said piston sliding on said tube and said pump having a driving member extending through said tube.

18. A hydraulic operator provided with a :Huid casing, a piston immersed in the fluid and movable therein, a load engaging member connected thereto, an impeller pum therein for creating a ressure diferentia to move said piston, ang a fluid guide tube extending through said piston to the inlet of said pump for conducting Huid thereto,

said piston sliding on said tube and said pump having a driving member extending through said tube.

19. An electro-hydraulic operator unit including a substantially closed container, a liquid therein, an electric motor mounted on the top of the container and having a shaft extending into said liquid, an operating member extending into said liquid through the top of the container, a piston connected to said operating member and immersed in said liquid, said piston being movable between two positions and biased to one of said ositions, an impeller pump connected to sa1d motor shaft and immersed in said liquid, a tube extending through said piston for conducting fluid to said pump, and other means disposed below the level of the liquid and cooperating with said tube for connecting the inlet and outlet of said pump to create a pressure differential on opposite sides of the piston to move said piston to the other position.

20. A hydraulic operator having a fluid casing, a piston therein movable between two positions and biased to one of said positions, a double inlet impeller pump in said casing for creating a fluid pressure therein to move said piston to the other position, a housing for said pump having a 'luid guide tube extending through said piston, said piston being slidable on said tube, a motor for driving said impeller pump and a drive shaft for connecting said motor and pum said shaft' extending through said gui e tube, said guide tube providing an inlet for said pump housing.

In witness whereof, I have hereunto set my hand this 29th day of September, 1930.

WILLIAM J. WOODS. 

